FunctionInfo.ts

import { AzureFunctionsRpcMessages as rpc } from '../azure-functions-language-worker-protobuf/src/rpc';
import { toTypedData, toRpcHttp } from './converters';

const returnBindingKey = "$return";

export class FunctionInfo {
  public name: string;
  public directory: string;
  public bindings: {
    [key: string]: rpc.IBindingInfo
  };
  public outputBindings: {
    [key: string]: rpc.IBindingInfo & { converter: (any) => rpc.ITypedData }
  };
  public httpOutputName: string;

  constructor(metadata: rpc.IRpcFunctionMetadata) {
    this.name = <string>metadata.name;
    this.directory = <string>metadata.directory;
    this.bindings = {};
    this.outputBindings = {};
    this.httpOutputName = "";

    if (metadata.bindings) {
      let bindings = this.bindings = metadata.bindings;

      // determine output bindings & assign rpc converter (http has quirks)
      Object.keys(bindings)
        .filter(name => bindings[name].direction !== rpc.BindingInfo.Direction.in)
        .forEach(name => {
          if (bindings[name].type === 'http') {
            this.httpOutputName = name;
            this.outputBindings[name] = Object.assign(bindings[name], { converter: toRpcHttp });
          } else {
            this.outputBindings[name] = Object.assign(bindings[name], { converter: toTypedData });
          }
        });
    }
  }

  /** 
   * Return output binding details on the special key "$return" output binding
   * Will be used in the future to address bugfix with breaking change: https://github.com/Azure/azure-functions-nodejs-worker/issues/228
   */
  public getReturnBinding() {
    return this.outputBindings[returnBindingKey];
  }
}